I found it before when comparing Greg's mini-WASP. They used the older 200mm f/1.8 which is now discontinued, and Canon has since bought out the f/2.

Still, I know they weren't going to be small lenses, but they're even bigger than I thought when they had someone standing next to them!

Side note: one question I've always had was of adequate image quality. The sensors they use are square, but are about 1.3x crop factor compared to the long side of 35mm film. I guess quality requirements are reduced somewhat as the sensors are "only" 4MP.

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Slightly off-topic but, for those not in the UK and who were unable to watch, the BBC's Stargazing program invited viewers to discover a new planet via planethunters.org over the three days that the Stargazing series ran for and guess what, they did!

Much puffing out of chests by all who took part is well deserved and, of course, the co-discoverers get additional glory. They may have only discovered a "hot Neptune" (closer to the parent star than the Goldilocks zone and so not a likely even possessing habitable moons) but seeing that happen live has to be one of the coolest things that I'll witness this year.